Drywall corner tools are commonly used to finish wall corners provided by adjacent intersecting walls. Many conventional drywall corner finishing tools in the marketplace are limited to applications against typical 90 degree angular inside corner wall joints. In recent years, the use of other angular measurements have been incorporated in building construction, resulting in larger and smaller angles than 90 degrees, such as vaulted ceilings or corner bay window coves.
Angles other than 90 degrees can be finished by hand using a joint knife or variable angle hand trowel. This method is very time consuming since each side of the angle must be finished separately and allowed to dry. To assist in this finishing process, a product called “corner bead” was made available in a variety of popular angles, which is placed into the corner to fill the joint gap and provide a straight vertical corner line before drywall compound (mastic or mud) is applied and finished by hand. Such corner bead strips, however, increase the cost of drywalling.
To alleviate problems associated with variable wall corner angles, drywall corner tools have been developed having adjustable corner angles. For example, such tools have been disclosed in U.S. Pat. No. 5,442,832, issued on Aug. 22, 1995; U.S. Pat. No. 5,467,497, issued on Nov. 21, 1995; U.S. Pat. No. 5,544,384 issued on Aug. 13, 1996; and U.S. Pat. No. 5,774,924, issued on Jul. 7, 1998. Each of these patents disclose corner tools having hinged blades for pivotal movement of the blades about the hinge axis to form a variety of corner angles. Slideably or pivotally connected arms extend between the blades to support the blades and adjust the blades to a desired corner angle. Typically, the angle is fixed by a locking member that prevents sliding or rotation of the arms about the handle prior to use. Alternatively, the '497 patent discloses a locking pin bolt extending through the hinge for fixing the blades at a desired angle.
In some cases, a particular wall corner angle is variable, either by design or because the corner is not true, such that fixedly variable angle corner tools may not adequately finish such a corner. Although it is possible to not fix the angle of the prior art corner tools to allow the blades to move together for adjusting to decreasing wall corner angles during use, the blades will not automatically return to their original position or adjust to increasing wall angles.
There is, therefore, a need for an improved adjustable corner tool.